A few years ago, with the 4 speed autos we had, you'd be cruising
along at highway speed at about 1800 RPM.
You'd go up a grade, and the RPMs would increase 500 RPM to maintain
speed. After this, the transmission would downshift to 3rd, and you'd be
taching about 2800 RPM.

That's how it went in my 95 Chevy, and probably my 91 Bronco before that.
The first change of RPM was the Torque Converter unlocking. Right?
It made for a smoother transition to the shift to 3rd, as that was just another
500 RPM increase.

So flash forward to today, with our 6 speed transmissions, and they do the
same thing. My question is why? Sometime going up a grade, when my truck shifts out of
6th, it goes to 5th with an increase of 500 or so RPM.

Other times, it does the unlock, staying in 6th with the same RPM
change.

I have no clue as to how an automatic transmission/torque converter works, but my question is: why do we still have this unlock in lieu of simply
downshifting to 5th each time? I thought I read someone's comment
here at one time, that driving with the TC unlocked was hard on it.


Also, can, or does the TC have the capability to unlock in any gear?